Octane selector

Topics about the engine, transmission, transfer, axles, or wheels/brakes of Chevy 1 1/2 ton trucks.

Octane selector

Postby Pop Larkin » Sun Dec 02, 2007 8:04 am

Does anybody know what an 'Octane selector' is? I have just put all new points, condenser, rotor, cap and HT leads on my 235 Chevy engine. In the manual it mentions setting the 'octane selector' to zero after checking the tension of the points spring and also that it is set to zero before adjusting the timing, but I can find no more info about the 'octane selector' in the manual. What is it?
Pop Larkin
 

Postby pfarber » Thu Dec 13, 2007 6:22 pm

My guess is that it some sort of ignition timing adjustment. It would be on the distributor mechanical or vacuum advance circuit.

Lower octane fuels would require less ignition advance due to their susceptibility to detonation.

My limited research put this as a 1930's era item on Chevy motors.
User avatar
pfarber
Motor Sergeant
 
Posts: 2839
Joined: Wed Oct 10, 2007 2:45 am
Location: The Internet

Postby Pop Larkin » Sun Dec 23, 2007 6:05 am

I have found out what it is now thanks. The clamp bracket which holds the distrubutor into the block is the Octane Selector. It is mounted to the block using a slotted hole, and has timing marks to change the timing by 10 degrees before and after TDC.

I have now setup the engine and she is running like brand new, I couldn't believe it was the same motor, so smooth and quiet 8)
Pop Larkin
 

Postby WWII TRUCK » Tue Dec 25, 2007 8:13 am

Kind of obsolete in this age higher octane fuels. Vacuum gage works better.
WWII TRUCK
 


Return to Engine/Drivetrain

cron